Light-weight building materials and their manufacture from synthetic anhydrous calcium sulfate



Patented Aug. 5, 1952 UNITED STATES PATENT OFFICE EXAMINER LIGHT-WEIGHTBUILDING MATERIALS AND THEIR MANUFACTURE FROM SYNTHETIC ANHYDROUSCALCIUM SULFATE Herman Weber, Harriman, Tenn.

No Drawing. Application March 25, 1949,

Serial No. 5 g9 Claims- (Cl.10687) This invention relates tolight-weight building stones, plates, insulating ma erials, e c., andmore specifically to the manufacture of products of this kind fromsynthetic anhygmns gamma-n sul- Mamaterial-I use the residue of theacturing h drofluoric aci rom ey occur 11 process, are an anhydrouscalcium sulphate, containing, according to the starting material (fluor-On an average, the

spar) certain im urities. residue contains, besides calcium sulphate,small varying amounts of sulp ur c acid, hydrofluoric acid, and alsoaluminum ox e, s con oxide, 1135 (Hide and calcium fluoride."

It is an object of this invention to provide expanded porous productsfrom said materials in a very simple and inexpensive manner.

Another object of the invention is the process of manufacturing productsof this kind, which 20- process requires a minimum of treatment andhandling 01' the raw material.

Other objects and advantages of this invention will become apparent fromthe following specifications thereof.

It has been discovered that th necessary for producing a cellularstructure in ight-weight building stones, plates, and insulatingmaterials can be developed before and during the setting process by theaction of mineral acids, e. g.

1- phurig acid, on cert'aifiiditabl siliebus merge-t r a s whichdecompose by action of mineral acids with accompany 8 evolution ofgases.

Suitable siliceous materials to be used according to this invention arehydrated combustion residues (fly ash, boiler or urnacecin ers, furnacgslag and othersl, or tmicates which decompose by action of mineral acids(e'. g. sulphuric acid) with evolution of gases. The sulphuric acid canbe of technical grade,@waste acid from various industrial processes suchas the silph'o'nat'ion" of or anic" cemeteries";

According to one embodiment of my invention, fresh unneutralizedresidues of the process of manufactu'ridg hydrofluoric acid are used asa raw material. In this case, no addition of acid is required forevolution of gases from the siliceous material. The residue of afineness to pass an 80 mesh sieve is mixed with appropriate amounts ofsilic egus piaterials and water as described in the following examples.

Suitable siliceous materials for this purpose are again the hydratedcombustion residues, smelter slags, or natural silicates as previouslydescribed, which decompose by action of the 2 suitable for interiorwalls and surfaces according to the properties noted.

No addition of any kind of accelerator is necessary as the settingagents are also liberated bv the action 0 he acid on the siliceousmaterial.

Percentexpansion;2530%. Density: 0.9-1.2

This density can be changed by controlling the amounts of acid in theresidue through partial neutralization, or by addition of more acid, orby varying the amount of siliceous material in proportion to the densityand strength required. The material is sawable, nailable, and fireresistant, and has excellent thermal and acoustical insulatingproperties. According to another embodiment of my invention the residueanhydrous calcium sulphate (Cg-S921 conta'fnfiig "small varying amountsof sulphuric acid (H2504) and hydrofluoric acid 272). is arairaagamrllthr lineages. dust (C'aCOaL ground to passan mesh sieve, mixed wappropriate amounts of suitable siliceous material and 2 /2-5% solutionof sul hfiflda'cid' as described in Example 1.

If residues are used which are derived 559m a waste d unfiiand whichhave been exposed to wdthef'a'rid thereby neutralized, no furtherneutralization with limestone dust or other basic substances isrequired.

When poured into molds, the mixture will expand due to the formation ofgasesresulting from the action of the acid on the" siliceous materials,and set to form porous stons'fblockibrlcks, or plates suitable forinterior walls and surfaces according to the properties noted.

No addition of any kind of accelerator is necessary as the neededsetting agents are also liberated by the action of the acid on thesiliceous materials.

Example 2 By weight 00 parts tra anhdrous $13 391} sggwlpggfi msidue 50parts oun as or 0 er y rs e s ceous materials) 50 partsagueouffilp'flhric acid (5%) Test results: Age 7 days l28daysCompressionresistance (pounds p. s. i) 550% 1,000%

Density: 0.9-1.2

This density can be controlled by varying the amounts of acid orsiliceous material used to cause the expansion. The blocks are ready foruse after drying in atmospheric storage for 8-10 days; or after beingkiln dried at 50-80" C. for one day. The material is sawable, nailsble,and fire resistant, and has excellent thermal and acoustical properties.

Having described my invention, what I claim is:

1. A plaster composition capable of setting with a porous cellularstructure if treated with water, consisting, by weight, of about 100parts of acidulous synthetic anhydrous calcium sulfate residues derivedfrom the process of manufacturing hydrofluoric acid; and about 50-75parts of a siliceous material which decomposes by the action of acidunder an evolution of gas, said siliceous material being selected fromthe group consisting of hydrated combustion residues, fly ash, smelterslags and cinders.

2. A plaster composition capable of setting with a porous cellularstructure if treated with a weak solution of a mineral acid, saidcomposition consisting, by weight, of about 100 parts of neutral orneutralized synthetic anhydrous calcium sulfate residues derived fromthe process of manufacturing hydrofluoric acid from fluorspar bytreatment with concentrated sulfuric acid; and about 50-75 parts of asiliceous material which decomposes by the action of acid under anevolution of gas, said siliceous material being selected from the groupconsisting of hydrated combustion residues, fly ash, smelter slags andcinders.

3. The process of manufacturing porous lightweight building materials,as stones, plates, blocks, insulations, etc., which consist in mixing100 parts by weight of the acid residues accruing from the process ofmanufacturing hydrofluoric acid from fluorspar by treatment withconcentrated sulfuric acid, said residues consisting chiefly ofsynthetic anhydrite and small amounts of sulfuric acid and hydrofluoricacid, with about 50-75 parts of a siliceous material which decomposes bythe action of acid under an evolution of gas, said siliceous materialbeing selected from the group consisting of hydrated combustionresidues, fly ash, smelter slags and cinders; pouring this materialmixed with water into molds wherein by the action of the acids containedin said residues said siliceous materials are decomposed under evolutionof gases and expansion of the plastic mass.

4. The process of manufacturing porous lightweight building materials,as stones, plates, blocks, insulations, etc which consists in mixing 100parts by weight of neutral residues derived from the process ofmanufacturing hydrofluoric acid from fluorspar with concentratedsulfuric acid, said residues consisting mainly of synthetic anhydrite,with -75 parts of a siliceous material selected from the groupconsisting of hydrated combustion residues, fly ash, cinders, smelterslags; pouring this material mixed with a 2 -5% solution of sulphuricacid into molds. wherein under the action of said sulphuric acid saidsiliceous materials are decomposed under evolution of gas andexpansionof the plastic mass.

HERMAN WEBER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 230,151 Sanford July 20, 18801,597,093 Malloy Aug. 24, 1926 1,951,691 Coxon Mar. 20, 1934 FOREIGNPATENTS Number Country Date 524,147 France 1921 401,190 Germany 1924706,007 Germany 1941

1. A PLASTER COMPOSITION CAPABLE OF SETTING WITH A POROUS CELLULARSTRUCTURE IF TREATED WITH WATER, CONSISTING, BY WEIGHT, OF ABOUT 100PARTS OF ACIDULOUS SYNTHETIC ANHYDROUS CALCIUM SULFATE RESIDUES DERIVEDFROM THE PROCESS OOF MANUFACTURING HYYDROFLUORIC ACID; AND ABOUT 50-75PARTS OF A SILICEOUS MATERIAL WHICH DECOMPOSES BY THE ACTION OF ACIDUNDER AN EVOLUTION OF GAS, SAID SILICEOUS MATERIAL BEING SELECTED FROMTHE GROUP CONSISTING OF HYDRATED COMBUSTION RESIDUES, FLY ASH, SMELTERSLAGS AND CINDERS.